SAS comes out fighting as details of top-secret missions are exposed

Senior officer banned from elite unit's HQ over tell-all book, while its commander takes aim at US general for breaking code of silence on operations

Britain's elite fighting force, the SAS, has become enmeshed in controversy and recriminations, with one of its most successful former senior officers being banned from headquarters and its current chief engaged in a dispute with the US commander of Nato forces in Afghanistan.

The Independent has learned that General Stanley McChrystal, leading Western troops in the war against the Taliban, has received a complaint from the UK's Director of Special Forces (DSF) after he broke the SAS's code of silence and spoke about the missions mounted by the SAS and their Royal Marines equivalent, the SBS, in Iraq and Afghanistan.

At the same time, Lieutenant-Colonel Richard Williams, who led the SAS during the Iraq war in undercover operations run by General McChrystal, has been told to stay away from the regiment's headquarters in Hereford.

The controversy comes at a time when General Sir David Richards, the head of the British Army, has asked the DSF, a Major-General who cannot be named for security reasons, to consider whether there should be greater transparency about the actions of his troops now carrying out vital missions in Afghanistan.

The regiment, however, is engaged in an internal inquest about past and current members who helped in writing a book about the Iraq mission. In a fallout from this, Colonel Williams, credited with playing a key role in the special forces operations in Iraq that led to the deaths or capture of around 3,500 insurgents, has been told to stay away from headquarters.

Colonel Williams, a highly decorated soldier, had enthusiastically backed General McChrystal's stance during the Iraq war, that rather than hunt for Saddam Hussein's mythical WMD arsenal and track down ageing Ba'athists, the Coalition special forces should concentrate on al-Qa'ida, whose members had come into the country in the wake of the US-led invasion.

The SAS has, in the past, proved to be unforgiving towards those who it considers to have broken the code of "omerta" (vow of silence) about its activities. General Sir Peter de la Billiere, the commander of British forces in the first Gulf War, and a former DSF, also became persona non grata in Hereford after including a chapter in his memoirs about special forces operations.

Colonel Williams, who unexpectedly left the Army when, it was felt, he was heading for the very top, has refused to comment about his banishment. But he is believed to have strenuously denied that he was a source for the Iraq book, written by Mark Urban, the defence and diplomatic editor of the BBC.

Prior to publication, lawyers representing Urban and the Ministry of Defence had been in negotiations for months over what can appear in the book without compromising national security.

The DSF and some of his senior colleagues are said to have been adamant that information about operations contained in the manuscript would be damaging for future missions, and fought a long rearguard action to keep out as many of the details as possible.

The book, which was published last February, reveals the identities of some special forces' personnel while protecting those of others.

Friends of Colonel Williams point out that his name was among those the MoD chose not to ask to be changed in the published version, thus leaving him and others open to unfair accusations of collusion with the author.

But it is the rift with General McChrystal, the high-profile commander tasked by US President Barack Obama to turn the tide of the Taliban insurgency, which is causing the most concern in the defence field on both sides of the Atlantic. The American commander incurred the displeasure of the DSF by giving a newspaper interview in which he was effusive in his praise of the UK special forces in Iraq and Afghanistan. The British Major-General apparently felt that General McChrystal had no business talking about the activities of British troops.

The DSF's complaint, according to American sources, had "surprised and bemused" General McChrystal, who stood up for British forces against criticism by some US officers in Baghdad during the Iraq conflict. Such was the esteem in which he was held that General McChrystal was asked to address a gathering of British special forces following a service of thanksgiving at Hereford at the end of the Iraq mission – which he insisted in doing, during a particularly busy time in Afghanistan.

General McChrystal has also sought out and appointed Major-General Sir Graeme Lamb, a former director of special forces himself, who he had worked with in Baghdad, to head the programme to win over insurgent fighters in Afghanistan – a key part of the West's exit strategy from the war.

It was a role that General Lamb had fulfilled in the Iraq campaign, leading to the so-called "Sunni awakening" in which Iraqi nationalist fighters turned their guns against al-Qa'ida. General Lamb's name also appears in Urban's book although he does not, it is believed, face sanctions from the DSF.

The thanksgiving service that General McChrystal attended was a poignant and evocative occasion, with the rendition of two pieces of John Bunyan's The Pilgrim's Progress, adopted by the SAS, who call themselves "pilgrims", as their battle hymn.

The hymn, which ends, "He will not fear what men say, he will labour night and day, to be a pilgrim", was roared out by the special forces veterans at Hereford Cathedral.

One senior officer present there said yesterday: "In fact, they do care an awful lot about 'what men say'. For men so tough the SAS seem to be remarkably sensitive. One questions the wisdom of telling off Stan McChrystal, who has been a good friend of the British; and banning Richard Williams on unproven suspicion is pretty harsh."